1. Field of the Invention
The present invention relates to a detection or an improvement of a jet failure of a nozzle in an ink jet printer.
2. Description of the Related Art
In an earlier developed ink jet printer, an image is recorded by jetting ink droplets onto a recording medium from a plurality of nozzles which use a thermal system or a piezo system actuated according to jet signals based on image signals. In the ink jet printer, fixing of ink near nozzle jet openings or adhering of impurities (foreign particles) or the like to the nozzle jet openings due to drying or increased viscosity of ink in a case of being left for a long period of time without being used would cause clogging of the nozzles, which results in a failure of jetting ink droplets from the nozzle jet openings in spite of normally outputting ink jet signals from a drive circuit unit, that is, a jet failure of ink from the nozzles (hereinafter, referred as nozzle clogging). The nozzle clogging would cause a deterioration of print quality such as generating a blank in a printed character or image, which is recognized as a white stripe, or causing difference of reproduced color in each recorded image due to a lack of ink color material. Therefore, an optical detection section as a detection section for detecting such the nozzle clogging is disclosed.
For example, disclosed is an ink jetting condition detection method for detecting nozzle clogging by changing a detection timing with a photo sensor in which light emitting elements and light receiving elements are combined along a distance corresponding to the width of the head as a detection section of nozzle clogging of a carriage type ink jet printer in which ink is jetted from a head in a direction (main scanning direction) perpendicularly crossing a carrying direction of a paper (sub scanning direction) to form an image (JP-Tokukai-hei-11-188853A, hereinafter referred as “Patent Document 1”).
Also, disclosed is an ink jet recording apparatus in which an opening is provided in an endless belt for performing a cleaning of a head of a line head type ink jet recording apparatus in a short period of time, and a maintenance operation is performed on a carrying path of a recording medium without moving the recording head (JP-Tokukai-2001-287377A, hereinafter referred as “Patent Document 2”).
However, applying Patent Document 1 to a line head type ink jet printer could be causative factors of cost increase due to the needs to adjust the amount of light or the diameter of beam from the light emitting elements with high accuracy because one line head has a large length, and to move the detection section for nozzle clogging by using a positioning sensor with high accuracy. Also, the distance between the light emitting elements and the light receiving elements becomes large, which may cause misdetection due to dust or ink droplets in the form of mist.
Further, since a plurality of nozzles which need to be detected exist in one line head, it would raise a problem that time for detection become long.
Also, in a case of applying Patent Document 2 to a line head type ink jet printer, it is disclosed that the opening is provided in the carrying belt to perform cleaning and maintenance, however, there is no disclosure to detect nozzle clogging.
As described above, in the earlier technique, the nozzle clogging detected is solved by a maintenance section, and then the printing operation is performed. Therefore, after the maintenance operation by the maintenance section, no confirmation is performed whether the nozzle clogging is solved, thus, possibility would remain that the nozzle clogging still exist. Performing the printing operation in this state would deteriorate print quality and thereby decline reliability to the apparatus.